melev- Hmmm maybe my fiance's accord

I'm pushing 250 and I can sit on any individual rung, or the frame, without it budging
justinpsmith- Man was I thirsty
super311fan- Thanks, I'm really surprised that, basically, I was able to build this thing in a day.
ctreefer- It's hard to tell from the pictures, but the 4x4s are actually a touch shorter than the frame, so they are pushed down to the carpet. The frame itself is a hair off the carpet. I think this will alleviate any issues you're concerned about. The part I'm concerned about is that the weight sits mainly on the beams as the tank is 25" and the exterior frame is actually 28"- 1.5" frame around where the actual tank is. However, if I remember my physics and "dispersion," a small amount of that force should be transfered to the upper frame because the plywood is a flat surface that spans past the tank.
I had considered adding some reinforcing brackets to the back 3 beams where they attach to the 4x4s since the joists will support a great deal of the weight. I really wasn't convinced I needed them; but since I have them on hand, I think I'll add those now.
T5PO- I'll eat your food and drink your drinks, but I wouldn't trust my skills with someone else's floor just yet. :mixed:
CulturedAquatic - Who says I'm done! I plan on adding more birch plywood to the inside slots that you see uncovered. I'm also going to seal it and poly it to make as nice of a shell as possible. Remember guys, this is a basement, so I'm a little less concerned about some of the same issues that would have bothered me if it was on any other level of the house. I'm basically dealing with concrete underneath.
The sump will be all the way to the right of the stand, the far left area I will leave open. That way if moisture does get down there, for any reason, there will be some ventilation.
I should also mention that the back bottom frame is a bit more flush with the carpet than the front. The front two pieces have a bit more of a bow up than the back two. This was one of your invaluable suggestions Bob- as I was extra mindful of keeping the crown up on all pieces. Thanks again for taking the time to answer the myriad of questions I fired at you.
Thanks again to all those who helped with their invaluable insight- Bob, Marc, Vince, and anyone else.